Power transmission formations such as splines or threads, etc. are rolled in workpieces by machines including a pair of spaced slides that respectively support a pair of forming racks. The forming racks utilized have oppositely facing toothed forming faces located on opposite sides of the workpiece initially in an end-to-end relationship. Hydraulic actuation of the slides moves the forming racks so that toothed forming faces engage the workpiece at diametrically opposite locations to roll the power transmission formations by plastic deformation. Such hydraulic actuation requires that there be continuous operation of a hydraulic pump since it is not practical to cyclically start and fully stop the pump for each workpiece roll forming cycle. Such continuous pump operation thus consumes energy that increases the cost of the resultant product.
Prior art hydraulically actuated machines are disclosed by U.S. Pat. No. 3,793,866 Anderson, et al.; U.S. Pat. No. 4,155,236 Jungesjo; U.S. Pat. No. 4,384,466 Jungesjo; and U.S. Pat. No. 4,519,231 Roth. These prior art machines have the rack slides thereof movable horizontally above and below the workpiece such that the rack movement is in a horizontal direction.